SOME CHEESE DEFECTS 373 



appear as a white felt, covering the surface of the cheese. 

 The acidity decreases and an alkaline condition is estab- 

 lished in the rind and a thin layer immediately beneath 

 it, softening and digestion of the curd occurring at the 

 same time. 



An excessive growth of Oospora lactis must be avoided, 

 as this leads to the production of an objectionable 

 flavour. 



3. Intermediate between the hard and soft cheeses are 

 Stilton, Gorgonzola, and other varieties which are drier, 

 firmer, and much larger than the soft forms, but not so 

 dense as the Cheddar and hard types. Upon the rind of 

 these kinds moulds and yeasts grow abundantly, and 

 after the lactic acid organisms have reached their maxi- 

 mum development and begun to disappear, the whole 

 body of the loosely-packed curd becomes penetrated by 

 the mycelium of a Penicillium. In the fissures in the 

 interior of the cheese the mould develops its characteristic 

 blue-green conidiophores, a well-ripened Stilton showing, 

 when cut across, a series of branching blueish veins. 



4. Some cheese defects, (i) Gassy or blown cheese. 

 One of the most frequent and most troublesome difficulties 

 with which the cheesemaker has to contend is the pro- 

 duction of " gassy " or " blown " cheeses, which invariably 

 possess a disagreeable flavour. Throughout the sub- 

 stance of the cheeses large numbers of more or less 

 spherical cavities or " bubbles " are formed. In some 

 cases the holes are not larger than a pin's head, while in 

 others they may grow to a large size, and give rise to 

 cheeses which are cracked, swollen, and distorted in 

 shape. 



The holes or bubble-like cavities are produced by 

 " gassy " fermentation of the milk-sugar, and develop 



